Firing mechanism with means for adjusting trigger-sear overlap



Feb. 27, 1968 s. G. o. LARSSON 3,370,374

FIRING MECHANISM WITH MEANS FOR ADJUSTING TRIGGER-SEAR OVERLAP FiledJan. 24, 1966 Patented Feb. 27, 1968 ice 3,370,374 FIRING MECHANISM WITHMEANS FOR ADJUSTING TRIGGER-SEAR OVERLAP Sven Gunnar Olof Larsson,Huskvarna, Sweden, assignor to Husqvarna Vapenfahriks Aktiebolag,Huskvarna, Sweden Filed Jan. 24, 1966, Ser. No. 522,498 Claims priority,application Sweden, Jan. 27, 1965, 1,039/65 Claims. (Cl. 42-69) ABSTRACTOF THE DHSCLOSURE A firearm in which a breech bolt is axiallydisplaceable in and withdrawable from a receiver with such breech bolthaving a striker and striker spring. A sear mounted on the receiver isprovided with a lug for releasably holding the striker in a cockedposition and the sear is provided with a shoulder. A spring pressedtrigger mounted on the receiver and having a cocking shoulder forreleasably holding the sear in its operative position by the engagementof and the overlapping of the sear shoulder. The cocking shoulder on thetrigger is retractable from the sear upon the pulling or squeezing ofthe trigger. A turnable adjusting means is operably related to the searand the trigger for adjusting the amount of the overlap and suchadjusting means is arranged so as to be accessible from the upper sideof the receiver upon the removal of the breech bolt. The adjusting meansis capable of reduc ing the overlap only to a predetermined safetylimit.

This invention relates to a firing mechanism for sliding bolt-actionfirearms, and more particularly to hunting and target rifles.

In such rifles, the trigger pull required for firing should beadjustable according to the individual requirements of the shooter andto different shooting circumstances. Such adjustments can usually bemade to some extent by eX- change or adjustment of parts of the firingmechanism after the rifle has been disassembled which, however, istroublesome and time-wasting. Furthermore, when assembling the rifle,particularly when screwing the bolt receiver to the stock, an elasticdeformation may occur which may require for example, an after-adjustmentwith file and emery cloth of an exteriorly accessible cocking lug on thesear. Moreover, in rifles in which the trigger moves such a scar lug outof cocking engagement with the striker of the breech bolt, the length ofthe trigger pull must be relatively long for reasons of safety,considering the relatively large vertical play of the striker. In theknown rifles provided with externably accessable turnable means foradjusting the amount of overlap of the cocking shoulders on the sear andtrigger, it is diflicult to reset such means in positions previouslytested and the overlap can be reduced to nil.

It is an object of the invention to eliminate the above drawbacks, andwith such and objects in view, as will hereinafter appear, the inventioncomprises the novel combinations and arrangements of parts hereinafterset forth and illustrated in the accompanying drawing, in which the solefigure shows a vertical longitudinal section through the pertinent partsof a bolt-action embodying the invention.

The bolt-action shown in cocked position comprises a receiver 1 screwedto a rifle stock 2 and a bottom plate 3 by means of a rear screw 4 and aforward screw (not illustrated). A breech bolt 5 is rectilinearlymovable in the receiver and withdrawable thereafter rearwardly, and asear 8 is pivotally mounted on the receiver by means of a pin 6. Thesear is provided with a spring 7, a shoulder 9 and an adjusting screw10. A trigger 13 is pivotally mounted on the receiver by means of a pin11 and is provided with a cocking shoulder 14 and a rear arm 15. Thebreech bolt 5 comprises a forward part 17 having a handle 16 and isturnable in its forward position. A striker in the shape of a firing pin19 is movable longitudinally, is actuated by a spring 18 and secured toa nut 20 having an obliquely downwardly directed contact surface 21 foran opposite surface 22 on a sear lug 3S situated in an aperture in thetail portion of the receiver. The adjusting screw It) has a slotted head23 countersunk into the sear 8, an edged portion 2 4 provided, forinstance, with two opposite chamfers or depressions, and engaged by apreferably ball-shaped, plunger 25 slidably mounted in the sear 8 andactuated by a spring 26, and a lower, conical terminal 27 engaging aplanar surface 28 on the trigger 13 said surface being approximatelyperpendicula to the retracting direction of shoulder 14 and deviatingconsiderably from the longitudinal direction of screw 10. The triggerspring 12 is confined between the arm 15 and a flanged nut 30 on anadjusting screw 31 having a slotted head 32 in a hole in receiver 1 anda flange 33 in contact with the underside of the receiver under thepressure of spring 12, the nut 39 being kept from turning 'by the sidesof a recess 29 in the receiver. The terminal of screw 31 forms anabutment for a set screw 34 in arm 15.

The firing pin is held in the cocked position shown by the sear 8, whichby the inclination of the surfaces 21, 22, is influenced by an obliquelydownwardly directed component of the pressure of the striker spring 18,but is held in operative position by the cocking engagement of theshoulders 9, 14. When the trigger is swung backwards manually, thecocking shoulder 14 is retracted and the firing pin thrown forward, thescar being depressed by the surface 21 against the action of spring 7which keeps the sear lug 35 in contact with the underside of nut 20 inthe forward position of the latter. When the trigger is released, spring12 brings cocking shoulder 14 into contact with a surface 36 on thesear. When the breech bolt together with its surface 21 is thereuponretracted the rear sear part is swung upwardly by spring 7, and spring12 causes cocking shoulder 14 to fall in front of shoulder 9. Bysubsequently advancing the breech bolt the cocked position shown isrestored. The rifle may in known manner be constructed as a repeatingrifle so that reloading after firing is done by turning up, retracting,advancing and turning down the handle 16.

The rearward motion of the trigger after firing is limited by the setscrews 31, 34 hitting one another. The length of this motion isadjustable by means of the set screw 34 before mounting the rifle actionin the stock and need not be altered thereafter. The weight and lengthof the trigger pull depends on the confinement length A of spring 12 andthe amount of overlap B of shoulders 9, 14, respectively. After removalof breech bolt 5 in a known manner, A and B can easily be adjusted bymeans of screws 31 and 10, respectively, with their heads 23 and 32being uncovered by such removal. Screw head 23 should be arranged toreach the bottom of its hole in the sear when screw terminal 27 has beenscrewed out so far that B has become reduced to a certain safetyminimum. By arranging the cocking engagement between the trigger andsear, and not as usual between the scar and the striker part 21, theoverlap becomes independent of the lateral play of said striker part sothat said minimum can be made very small, say 0.2 mm, Plunger 25 exertsa resistance against an adjustment of screw 10 and which resistancevaries with the angular position of said screw whereby one feels and cancount the number of turns or parts thereof through which the screw isbeing turned, thereby simplifying resetting the screw is positionspreviously tested.

In the embodiment shown, the trigger shoulder 1 is retractablerearwardly, and sear 8 is mounted to swing clockwise upon firing. Theinvention can be applied also to bolt-actions wherein the trigger ispivoted below its shoulder and the latter is retractable forwardly, withthe sear being mounted to swing counter-clockwise. Instead of anadjusting screw or threaded setting rod 10, one can also use asettingrod which is only rotatable in the scar and which at its lower endcarries a setting member in the shape of an eccentric engaging thetrigger in the cocked, operative position of the sear. Also othermodifications are possible within the scope of the claims which follow:

This invention is not to be confined to any strict conformity to theshowings in the drawings but changes or modifications may be madetherein so long as such changes or modifications mark no materialdeparture from the spirit and scope of the appended claims.

I claim:

1. A bolt-action firearm comprising in combination: a receiver, a breechbolt axially displaccable in said receiver, and withdrawable therefrom,said bolt including a striker and a striker spring, a sear mounted onsaid receiver and having a lug for releasably holding said striker in acocked position, a shoulder on said sear, a spring-pressed triggermounted on said receiver and having a cocking shoulder releasablyholding said sear in its operative position by engaging and overlappingsaid sear shoulder and retractable therefrom by pulling said trigger,turnable adjusting means operably related to said sear and said triggerfor adjusting the amount of said overlap, said adjusting means beingarranged to be accessible from the upper side of said receiver uponremoval of said breech bolt and said adjusting means being capable ofreducing said overlap only to a predetermined safety limit.

2. A bolt-action firearm comprising in combination: a receiver, a breechbolt axially displaceable in said receiver and Withdrawable therefrom,said bolt including a striker and a striker spring, a sear mounted onsaid receiver and having a lug for releasably holding said striker in acocked position, a shoulder on said sear, a springpressed triggermounted on said receiver and having a cooking shoulder releasablyholding said sear in its operative position by engaging and overlappingsaid sear shoulder and retractable therefrom by pulling said trigger,and two trigger pull adjusting rods turnably mounted in different partsof said bolt-action and each having a slotted end accessible from theoutside of said receiver upon removal of said breech bolt, one at leastof said rods having fixed thereto a flange wider than its slotted endand permanently engaging the part mounting said one rod so as to preventremoval thereof in the direction of its slotted end.

3. A bolt-action firearm comprising in combination: a receiver, a breechbolt axially displaceable in said receiver and withdrawable therefrom,said breech bolt including a striker and a striker spring, a searmounted on said receiver, a lug on the sear for releasably holding saidstriker in a cocked position, a shoulder on said sear, a springpressedtrigger mounted on said receiver, a cooking shoulder on said triggerreleasably holding said sear in its operative position by engaging andoverlapping said sear shoulder and being retractable therefrom bypulling said trigger, and two trigger pull adjusting rods turnablymounted in different portions of said bolt-action and each having aslotted end accessible from the upper side of said receiver upon removalof said breech bolt, said rods and said portions mounting same havinginterengaging means for arresting said rods in positions out of the pathof said breech bolt.

4. A bolt-action firearm comprising in combination: a receiver, a breachbolt axially displaceable in said receiver and withdrawable therefrom,said bolt including a striker and a striker spring, a sear mounted onsaid receiver and having a lug for releasably holding said striker in acocked position, a shoulder on said sear, a spring-pressed triggermounted on said receiver, said trigger having a cocking shoulderreleasably holding said sear in operative position by engaging andoverlapping said sear shoulder and being retractable therefrom bypulling said trigger, and an adjusting rod mounted in said sear foradjusting the amount of said overlap, said adjusting rod being arrangedto be accessible from the upper side of said receiver upon the removalof said breech bolt and engaging said trigger in a cocked position ofsaid striker, and a spring-pressed member mounted in said scar andengaging a non-circular portion provided on said rod.

5. A bolt-action firearm comprising in combination: a receiver, a breechbolt axially displaceable in and Withdrawable from said receiver, saidbreech bolt including a striker and a striker spring, a single searmounted on said receiver and having a lug for releasably holding saidstriker in a cocked position, a shoulder on said sear at one extremitythereof, a spring-pressed trigger mounted on said receiver and havingopposite said sear extremity a cocking shoulder releasably holding saidsear in an operative position by engaging and overlapping said searshoulder and being retractable therefrom by pulling said trigger, and asubstantially vertical rod rotatably mounted in said sear for adjustingthe amount of said overlap by contacting a planar surface on saidtrigger, the upper end of said rod being countersunk in said sear lugand accessable from the upper side of said receiver upon rem-oval ofsaid breech bolt, the retraction direction of the trigger considerablydeviating from the longitudinal direction of said rod.

References Cited UNITED STATES PATENTS 1,239,124 9/1917 Nelson.

1,741,281 12/1929 Burton 4269 2,069,887 2/1937 Laudensack 4269 2,249,2317/1941 Smith 4269 2,274,195 2/1942 Garrison 4269 2,584,299 2/1952Sefried 42-69 BENJAMIN A. BORCHELT, Primary Examiner.

